Cheney led an effort in 2003 to discredit former acting ambassador in Iraq, Joseph Wilson IV, who had written an op ed for the New York Times detailing his own mission to discover if Iraq was getting uranium from Niger.
Cheney had staffers contact journalists and inform them that Wilson’s wife, Valerie Plame, was secretly a CIA operative. While Cheney wasn’t the one whose phone call revealed this information, he set in train the events whereby it became well known.
What Cheney did by ordering his aides Scooter Libby and Karl Rove to release the information about Plame’s identity was no different from Edward Snowden’s decision to contact the press.